1. Technical Field
The present invention generally relates to an ink-jet system, particularly, to an apparatus for regulating air pressure in an ink tank and an ink-supplying system having the same.
2. Description of the Related Art
A liquid crystal display typically utilizes a color filter to display images and graphs. The color filter is constructed by arranging the colored portions, which are colored in red (R), green (G), and blue (B), as three primary colors of light on a transparent substrate. A dyeing method, a pigment dispersing method, an electrodepositing method, and the like are generally used as manufacturing methods for the color filter. Recently, an ink jet method has been used.
The ink jet method is different from other conventional methods and is a method in which each of R, G, and B inks are sprayed onto a substrate from respective nozzles of an ink jet device to form a color layer. When this method is employed, the required amount of ink can be applied onto a required area at a specific time. Accordingly, there is no waste of ink. Furthermore, since the sub-pixels of R, G, and B can be formed simultaneously, the printing process is shortened, and it is possible to markedly reduce cost.
Generally, the ink-jet device includes at least one print head. The at least one print head includes a plurality of nozzles. A respective nozzle connects to a respective ink reservoir configured for containing ink supplied by an ink tank.
The print head has certain disadvantages to its own. For example, when the print head is not in use, ink will sink out from the nozzles. To resolve this problem, a vacuum pump is usually used to maintain an air pressure in the ink tank below atmospheric pressure (i.e., substantially less than 760 mm Hg), in order to prevent the ink from sinking out from the nozzles. However, the vacuum pump is likely to create a concussive/fluctuated pressure, which affects the degree of vacuum in the ink tank. As a result, size of ink droplets becomes unstable, thus the quality of color filter made by the ink-jet device is decreased.
What is needed, therefore, is an apparatus which can stably adjust air pressure in the ink tank and a ink-supplying system with the same.